There is known a rotating electrical machine which uses a permanent magnet as a stator, in which consideration is made so that, even when the permanent magnet is damaged due to shock and the like from the outside, a fragment of the permanent magnet does not cause rotation failure of an armature serving as a rotor. Conventionally, as a rotating electrical machine of this type, there has been proposed a field device of a rotating electrical machine described in Patent Literature 1. The rotating electrical machine described in Patent Literature 1 includes a magnet cover formed of a thin plate, which covers an inner diameter portion (inner peripheral surface) and both circumferential side surfaces of the permanent magnet, and a magnet holder including retaining portions interposed between the respective permanent magnets, for retaining the respective permanent magnets in a circumferential direction, and annular portions located at both axial end portions of each permanent magnet, for retaining the respective permanent magnets in an axial direction. The magnet cover includes locking portions nat both circumferential end portions thereof, and the retaining portion of the magnet holder includes an engaging portion which engages with the locking portion of the magnet cover. The engaging portion engages with the locking portion of the magnet cover, and thus the permanent magnet and the magnet cover are retained and fixed in an inner diameter direction. Therefore, even when the permanent magnet is damaged, the magnet cover covers the inner peripheral surface and both the circumferential side surfaces of the permanent magnet, and hence the fragment of the permanent magnet does not fly into the armature, and rotation failure of the armature is prevented.